The method disclosed monitors the status of a network by a network
management system that includes information describing the current
network topology information describing possible restoration routes. From
this information, the network management system computes three measures
of network health: (1) the sum of unrouted permanent virtual circuits,
(2) the sum of permanent virtual circuits whose cost exceeds a prescribed
multiple of an optimal route cost and (3) the sum of permanent virtual
circuits off an optimal path. Each of these measures relates to a
different aspect of network health, and collectively they provide a
measure of overall network performance. The method compares the measures
of network health to a threshold value and selects an optimum restoration
route from the stored restoration routes.